The present invention generally relates to portable display devices, and more particularly, to portable display devices that can operate in both near-view and projection modes, which enables the devices to be used as both individual displays and multiple-viewer displays.
Generally, cameras are equipped with some type of viewfinder that operates to enable a user to view the scene that will be captured by the lens of the camera. In some cameras, this viewfinder may be something as simple as a port through the camera that allows the user to visualize the approximate boundaries of the image to be captured. In this regard, the user is then able to substantially determine beforehand what the resulting picture will look like. However, as can be appreciated, these ports do not permit the user to subsequently view the resulting image after the camera has taken a picture.
With the invention of digital cameras, manufacturers began including small electronic displays to allow users to view the image to be captured, and to subsequently view or playback previously captured images and/or videos. Rather than conventional cathode ray tube (CRT) displays, digital cameras typically utilize transmissive displays due to their relatively greater luminance, higher contrast ratios, greater sharpness, and better spatial uniformity. Generally, transmissive displays utilize a light source, often termed a backlight, to illuminate pixels on a flat, transmissive panel. Light intensity from the backlight may be maintained at a constant level, and color may be provided by the relative luminosity of the light transmitted through three primary color filters, usually selected as red, green, and blue, associated with each pixel on the panel. One example of transmissive display systems is Liquid Crystal Display (LCD) devices. An LCD is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source, such as a digital camera's backlight. LCD's are often utilized in battery-powered electronic devices, such as digital cameras, because they use relatively small amounts of electric power, are small in size and weight, and have reduced glare.
Typically, a digital camera includes an LCD screen affixed in the camera body. For example, the LCD screen may be affixed in a back wall of the camera body. In this regard, a user may preview the image to be captured, view stored images, and operate various menus on the digital camera. The LCD device may generally have a diagonal dimension of about one to four inches. As can be appreciated, these LCD devices may have disadvantages. First, only one person can easily monitor the image of the object being framed or previously framed through the viewfinder in the digital camera. That is, several people cannot simultaneously monitor the image of the object presently or previously framed since the display is quite small (e.g., 1-4 inches diagonal). Second, although many digital cameras provide features that enable them to be connected to an external display (e.g., a television, monitor, or external projector), it may be inconvenient to connect a digital camera to an external display when many persons are to simultaneously view the image or video shot by the digital camera.
Some efforts have been made to provide a camera that can also project an external display. However, these devices have typically required complex laser systems, costly redesigns, additional external components, and the like. Hence, there remains a strong demand for a dual-purpose digital camera that can both capture still or video images and play them back locally and to groups (e.g., projection).